JB/T 7025-1993 Technical requirements for rotor and main shaft forgings of steam turbines below 25MW
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T 7025—1993
Technical conditions for rotor body and main shaft forgings for steam turbines below 25MW
Issued on September 21, 1993
Ministry of Machinery Industry of the People's Republic of China
International Standard Download Network (www.bzxzw.com)
Implementation on July 1, 1994
Mechanical Industry Standard of the People's Republic of China
Technical conditions for rotor body and main shaft forgings for steam turbines below 25MW
Subject content and scope of application
JB/T7025—1993
This standard specifies the technical requirements, inspection rules, test methods, certificates and marks of carbon steel and alloy steel forgings for rotor body and main shaft of steam turbines below 25MW (including 25MW). This standard applies to carbon steel and alloy steel forgings for rotor bodies and main shafts of steam turbines below 25MW (including 25MW). Reference standards
GB 222
GB 229
GB4236
GB 6394
GB 6395
GB6397
GB10561
JB1581
ZBJ32005
JB/ZQ6101
JB/ZQ6134
3Ordering requirements
Sampling method for chemical analysis of steel and allowable deviation of chemical composition of finished productsChemical analysis method for steel and alloys
Metal tensile test method
Metal Charpy (U-notch) impact test methodMetal Brinell hardness test method
Metal bending test method
Sulfur imprint of steel Inspection methods
Methods for determining average grain size of metals
Methods for high temperature tensile rupture test of metals
Metal tensile test specimens
Microscopic evaluation methods for non-metallic inclusions in steel Ultrasonic flaw detection methods for turbine and turbogenerator rotor and main shaft forgings Thermal stability test methods for turbine main shaft and rotor forgings Magnetic particle inspection methods for forged steel parts
Sulfur print test methods and evaluation of large shaft forgings 3.1 The purchaser shall specify the adopted standards, steel grades, forging grades, corresponding technical requirements, inspection items and inspection items other than those required by this standard in the order contract or order agreement. 3.2 The purchaser shall provide the order drawings of forgings indicating the sampling positions for mechanical properties tests and the deep finishing dimensions of the blade root groove. 4 Technical requirements
4.1 Manufacturing process
4.1.1 Smelting
4.1.1.1 Steel for forgings shall be smelted in an alkaline electric furnace. 4.1.1.2 Other smelting methods that can ensure the requirements of this standard are allowed with the consent of the purchaser. 4.1.2 Forging
4.1.2.1 The steel ingots used for forgings shall have sufficient removal to ensure that the finished forgings are free of shrinkage cavities and unacceptable segregation. Approved by the Ministry of Machinery Industry on September 21, 1993
Standard Download Network (www.bzxzw.com
Implementation on July 1, 1994
JB/T70251993
4.1.2.2 Forging equipment should have sufficient capacity to ensure that the entire cross section of the forging is forged through. During forging, the entire cross section should be fully deformed to obtain a uniform structure.
4.1.2.3 The end of the ingot with better quality should be close to the motor end. The axis of the forging roughly coincides with the center line of the ingot.4.1.3 Heat treatment
4.1.3.1 Forgings need to be normalized or annealed after forging.4.1.3.2 Performance heat treatment should be carried out after rough machining. Carbon steel forgings are allowed to be quenched and tempered with the consent of the purchaser.4. 1.3.3 Vertical hanging heating and cooling should generally be adopted for performance heat treatment. Horizontal heating can also be adopted with the consent of the purchaser. Strictly control the furnace temperature and holding time to obtain uniform mechanical properties. 4.1.3.4 The tempering temperature and cooling rate of forgings should be selected appropriately. Under the premise of meeting the performance requirements, the tempering temperature should be as high as possible, and the forgings should be cooled slowly after tempering to ensure that the residual stress of the forgings is not greater than 8% of the specified lower limit of the yield strength. 4.1.4 Stress relief treatment
4.1.4.1 Forgings are generally subjected to stress relief treatment by the supplier, and the temperature should generally be within the range of 15~50℃ below the actual tempering temperature. When the performance heat treatment tempering cooling rate is less than 25℃/h, stress relief treatment may not be performed. 4.1.4.2
4.1.5 Mechanical Processing
4.1.5.1 The delivered forgings shall conform to the dimensions and surface roughness specified in the order drawings. 4.1.5.2
When the supplier performs rough processing, test samples shall be reserved at the specified locations for acceptance by the ordering party. 4.1.5.3 If stress relief treatment is required for the forgings, it shall be carried out after rough processing. 4.1.5.4 For rotor bodies with center holes, the center hole processing shall be carried out after rough processing or before stress relief treatment. 4.2 Chemical composition
Unless otherwise specified in the contract, the melting chemical analysis composition of steel shall conform to the provisions of Table 1. 4.2.2
The product analysis of forgings shall conform to the provisions of Table 1, and deviations specified in Table 2 are allowed if the mechanical properties are qualified. Table 1
34CrMo
34CrM ol
34CrNi3Mo
20Cr3WMoV
Chemical composition
30CrIMo1V
25CrNiMoV
28CrMnNiV
Chemical composition
Allowable deviation
Mechanical properties
Upper limit of composition
Unless otherwise specified,
Cold bending angle 1》
Recommended steel
JB/T7025-1993
Continued Table 1
Allowable deviation of chemical composition
The mechanical properties of forgings shall comply with the provisions of Table 3
Upper limit of composition
Table 3 Mechanical properties
Note: The values in the table are minimum values.
34CrMo
34CrMo1A
34CrMo
34CrMo1A
28CrNiMoA
25CrNiMoV
1) Parts not specified in the order contract shall not be used as the basis for acceptance
34CrMo
34CrMo1A
25CrNiMoV
34CrNi3Mo
34CrNi3Mo
20Cr3WMoV
30CriMo1
4.4 Hardness uniformity
JB/T7025—1993
4.4.1 The hardness difference between points on the same arc surface shall not exceed 30HBS, and the hardness difference between points on the same axis shall not exceed 40HBS.
Hardness value is not used as acceptance basis.
4.5 Nondestructive inspection
4.5.1 General requirements
Forgings are not allowed to have defects such as cracks, white spots, shrinkage holes, folds, excessive segregation, etc. 4.5.2 Magnetic particle (or pickling) inspection
Unless otherwise specified, the supplier shall ensure that the magnetic particle (or pickling) inspection complies with the following provisions4.5.2.1 No defects greater than 1.5mm in length are allowed on the surface of the bearing part. No more than 5 defects with a length of 1~1.5mm are allowed on any 25cm area. No more than 15 defects are allowed on each bearing part. 4.5.2.2 No defects greater than 3mm in length are allowed on the outer cylindrical surface other than the bearing part. Note: The 25cm area refers to the rectangular area with a maximum side length of 15cm4.5.2.3 For defects that do not meet the above requirements, local grinding and polishing of the defects is allowed with the consent of the purchaser. The polishing depth should not exceed 1.6mm and should have a smooth transition with the surrounding surface. 4.5.3 Ultrasonic testing
Unless otherwise specified, ultrasonic testing shall comply with the following provisions. 4.5.3.1 Single scattered defects with an equivalent diameter less than 2mm shall not be counted. 4.5.3.2 No part of the rotor body shall have defects with an equivalent diameter greater than 5mm, and the blade root groove shall be deepened by 25mm. Defects with an equivalent diameter greater than 3mm are not allowed in the transmission end bearing and other parts. 4.5.3.3 Dense defects with an equivalent diameter greater than or equal to 2mm are not allowed. 4.5.3.4 No wandering signals and continuous defect signals are allowed. 4.5.3.5 Provide the measured data of the attenuation coefficient of the longitudinal wave 2~2.5MHz of the forging material. 4.5.3.6 The location of the equivalent single defect greater than or equal to Φ2mm shall be marked with three-dimensional coordinates and indicated in the certificate of conformity. 4.5.3.7 Defects exceeding the above requirements shall be reported to the purchaser and handled through negotiation between the two parties. Note: Dense defect signals refer to defect signals with a quantity of not less than 5 and an equivalent diameter of not less than 2mm in a cube with a side length of 50mm. 4.5.4 Center hole
4.5.4.1 For rotor forgings with a center hole, the surface roughness R value of the center hole is 3.2m. The surface of the center hole is not allowed to have dense areas composed of cracks, white spots, residual shrinkage holes, visible defect displays with a length greater than 4mm, and non-metallic inclusions. In addition, the following provisions: a. Defect displays with a length equal to or greater than 1.5mm shall record their axial and circumferential positions and report to the purchaser; b. Within an area of 60cm, there shall not be more than 10 small defect displays with a length of less than 1.5mm; c. Dispersed defect displays with a length of 1.5~3mm shall not exceed 10, and dispersed defect displays with a length of 3~5mm shall not exceed 5.
2 Defects beyond the above mentioned can be removed by grinding, the grinding depth shall not exceed 1.6mm, and the transition with the surrounding surface shall be smooth. The center hole can be enlarged with the consent of the party requiring 4.5.4.2
.
4.6 Straightness
When the forging is delivered, the straightness tolerance value of its axis is within the cylinder with a diameter of 3mm. 4.7 Metallographic structure
4.7.1 Grain size
When the grain size inspection is required, it shall be indicated in the order contract. Unless otherwise specified, the average grain size shall not be coarser than grade 4.0. 4.7.2 Inclusions
When the inclusion inspection is required, it shall be indicated in the order contract. Unless otherwise specified, the four types of inclusions A, B, C, and D shall not exceed grade 3.0.
4.7.3 Sulfur print test
JB/T 7025—1993
The buyer has the right to conduct a sulfur print test. The supplier does not conduct this test, but shall ensure that the result is not greater than level 3. If it is greater than level 3, the two parties shall negotiate to deal with it.
4.8 Cold bending
The buyer has the right to conduct a cold bending performance test. The supplier does not conduct this test, but shall ensure that the result complies with the provisions of Table 3. 4.9FATTso
When the FATTso value is required to be tested, it shall be indicated in the order contract, and the brittle transition temperature and the sample location shall be specified. 4.10 Thermal stability test
The buyer shall conduct a thermal stability test, and the supplier shall be responsible for the test results. 4.11 High-temperature mechanical properties
4.11.1 The rotor body of the same material, the same specification, and high-temperature operation produced for the first time shall be tested for high-temperature mechanical properties. 4.11.2 When the supplier is required to measure the high temperature mechanical properties, it should be indicated in the order contract and the sampling location and requirements should be specified. 5 Inspection rules and test methods
5.1 Chemical composition analysis
5.1.1 Each furnace of molten steel should be subjected to smelting analysis. 5.1.2 The samples for product analysis are taken from the tangential or longitudinal samples of the forgings. 5.1.3 The sampling of chemical composition analysis samples shall be in accordance with GB222. 5.1.4 Chemical composition analysis shall be in accordance with GB223 or other analysis methods that ensure the quality of analysis. 5.2 Mechanical Properties
5.2.1 Sample Sampling
Unless otherwise specified, mechanical properties samples are taken from forgings after performance heat treatment. The sampling locations are as follows: 5.2.1.1 Longitudinal Sampleswww.bzxz.net
a For forgings with a delivery weight of less than or equal to 1 ton, the supplier shall take 1 longitudinal tensile test specimen and 2 impact test specimens at 1/3 of the outer surface (without center hole) or 1/2 of the thickness (with center hole) at either end, and the purchaser shall take samples for acceptance at the other end. b. For forgings with a delivery weight of more than 1 ton, 1 longitudinal tensile test specimen and 2 impact test specimens shall be taken at each end. 5.2.1.2 Tangential Test Specimens
a For rotor forgings with a delivery weight of less than or equal to 6 ton, 1 tangential tensile test specimen and 2 impact test specimens shall be cut from the steam inlet end of the shaft. b. For rotor forgings with a delivery weight of more than 6 ton, 1 tangential tensile test specimen and 2 impact test specimens shall be taken at each end of the shaft. 5.2.1.3 When sawing is used for sampling, double specimens should be left on the forgings, and the specimen positions should be marked on the rough machining drawings. When nesting is used for sampling, the supply and demand parties share a shaft end specimen.
5.2.2 The preparation and cutting of tensile specimens should comply with the short proportion specimens specified in GB6397. 5.2.3 The tensile test shall be in accordance with the provisions of GB228, and the high temperature tensile test shall be in accordance with the provisions of GB6395. 5.2.4 The impact test shall be in accordance with the provisions of GB229. 5.3 Hardness uniformity
Performance Hardness uniformity inspection shall be carried out after heat treatment. 5.3.1 Inspection location
5.3.1.1 Spindle forgings: Measure 4 points at 90° on the outer circle of the two journals, for a total of 8 points. 5.3.1.2 Rotor forgings: Measure 4 points at 90° on the outer circle surface of the two journals and the shaft body of the forging, for a total of 12 points. 5.3.2 Hardness test method shall be in accordance with GB231. 5.4 Cold bending test
When cold bending test is required, a 10mm×20mm×160mm specimen shall be taken from the shaft end, the edge of the specimen shall be an arc with a radius of 1mm, and the bending core diameter shall be 40mm. The test method shall be in accordance with GB232. 5
5.5 Pickling or magnetic particle inspection
Pickling or magnetic particle inspection shall be carried out at the demand side. JB/T7025-1993
5.5.1 After semi-rough machining, pickling or magnetic particle inspection shall be carried out on the bearing part, shaft end face and shaft transition zone. 5.5.1.1 After rough machining, a surface macroscopic inspection shall be carried out, and a magnetic particle inspection may be carried out if necessary. The surface roughness R value of the inspection part shall be 3.2μm. 5.5.2 The magnetic particle inspection method shall be in accordance with JB/ZQ6101 or other recognized methods. 5.5.3 Pickling inspection method
The surface roughness R of the pickled area is 1.6um. When pickling, first use 15% ammonium persulfate aqueous solution, then use 10% nitric acid aqueous solution, and the pickling time is not less than 15min respectively. After pickling, two inspections are carried out, the first inspection is 10min after pickling, and the second inspection is not less than 12h after pickling.
5.6 Ultrasonic inspection
5.6.1 Ultrasonic inspection should be carried out on all detectable surfaces of forgings after quenching and tempering and rough machining. 5.6.2 For forgings that need to be reheat treated, ultrasonic inspection should be carried out again after reheat treatment. 5.6.3 The ultrasonic inspection method shall be in accordance with the provisions of JB1581. 5.7 Thermal stability test
When thermal stability test is required, it should be carried out on the demand side. The inspection method shall be in accordance with the provisions of ZBJ32005. 5.8 Center hole inspection
5.8.1 For rotor forgings with center holes, the center hole size and inner hole surface shall be inspected. 5.8.2 Unless otherwise specified, inspection shall generally be carried out with a peep instrument. 5.9 Metallographic inspection
5.9.1 Unless otherwise specified, the sample for determining the grain size shall be taken from the tangential sample of the body, and the spindle shall be taken from the longitudinal sample of the shaft end. The inspection method shall be in accordance with the provisions of GB6394.
5.9.2 Unless otherwise specified, the sulfur print inspection method shall be in accordance with the provisions of GB4236. The sulfur print rating is limited to transverse sections and shall be carried out in accordance with JB/ZQ6134.
Unless otherwise specified, the inclusion inspection method shall be evaluated in accordance with the rating diagram I in Appendix A of GB10561, and the sampling location shall be the same as that specified in Article 5.9.1 of this standard.
5.10 Residual stress
5.10.1 Residual stress shall be checked before forgings leave the factory, and the specimen shall be taken from the same part of the forging where the specimen is cut. 5.10.2 The residual stress shall not be measured for rotor bodies with impeller diameters less than Φ300mm and the main shaft. 5.10.3 Unless otherwise specified, the residual stress is generally determined by the ring cutting method and the ring core resistance strain method. The ring cutting method takes a circular ring with a sample size of 25mm×25mm, and the residual stress is calculated by measuring the average deformation of the ring before and after cutting. 5.10.4 Residual stress calculation formula:
Where: O Residual stress, MPa:
s Algebraic value of diameter increment, mm
D Outer diameter of the ring before cutting, mm
E—Elastic modulus of the material, MPa
5.11 Retest
5.11.1 Retest is allowed when the mechanical properties test results do not meet the specified requirements. However, if the specimen fails due to white spots or cracks, retesting is not allowed.
5.11.2 If a test result fails due to equipment failure or poor specimen preparation, a sample can be taken from the adjacent position of the forging for retesting. 5.11.3 If one of the tensile test results does not meet the requirements, two additional specimens should be taken from the adjacent position for tensile testing. The test results of the two specimens should meet the requirements. 6
JB/T7025—1993
5.11.4 Retesting is allowed when the room temperature impact value is lower than the specified lower limit. During the retest, two additional specimens should be taken from the adjacent position for impact testing. The impact values of the two specimens should meet the requirements of Table 3. 5.12 Reheat treatment
5.12.1 When the retest results of any mechanical property of the forging are still unqualified, reheat treatment and resampling are allowed. 5.12.2 The number of re-heat treatments of forgings shall generally not exceed 2 times (referring to re-heating). Acceptance and Certificate of Qualification
6.1 The supplier shall provide the necessary convenience to the purchaser's inspector so that the purchaser's inspector can carry out his work. 6.2 The purchaser has the right to select certain acceptance test items for forgings. If it is found in the acceptance test or in the subsequent processing or test that the forgings do not meet the supplementary technical requirements specified in this standard and the order contract, the purchaser shall promptly notify the supplier and the two parties shall negotiate to resolve the problem. 6.3 The supplier shall provide the purchaser with a certificate of conformity, which shall include the following: a. Contract number:
b. Forging drawing number:
c. Standard number, forging grade and steel type;
d. Melting furnace number and melting method:
e. Melting analysis and finished product analysis results;
f. Main dimensions of steel ingots and actual forging ratio of forgings: g. Actual temperature, holding time and cooling method of each heat treatment; h. Test results of mechanical properties;
i. Results of other tests and supplementary tests required by the purchaser: j. Actual dimensions and weight of delivered forgings.
7 Marking and packaging
7.1 The supplier shall mark the contract number, furnace number, part number, etc. on the lower part of each forging, which is equivalent to the lower part of the steel ingot, and circle it with white paint. 7.2 The supplier shall apply rust preventive agent to the outer surface and center hole surface of each forging, and plug the center hole with wooden plugs at both ends to prevent damage or corrosion during transportation and storage.
Additional Notes:
This standard is proposed and managed by the Deyang Large Castings and Forgings Research Institute of the Ministry of Machinery Industry. This standard is drafted by the Deyang Large Castings and Forgings Research Institute. The main drafters of this standard are Jiang Xinliang, Zhang Xiushan, Tian Yunjiang, and Liu Xiaoguang. 7
People's Republic of China!
Mechanical Industry Standard
Steam Turbines Below 25MW
Technical Conditions for Rotor Body and Main Shaft Forgings
JB/T7025-1993
Published and Distributed by China Academy of Mechanical Science
Printed by China Academy of Mechanical Science
(No. 2 Shouti South Road, Beijing
Postal Code 100044)
4Number of Words 14,000
Format 880×1230
Sheet 3/4
First Edition in May 1994
First Printing in May 1994
Print Quantity 1-500
Price 6.00 Yuan
Mechanical Industry Standard Service Network: http://www.JB.ac.cn6
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